Infidelity of DNA synthesis associated with bypass of apurinic sites.

AUTOR(ES)

Schaaper, R M

RESUMO

The mutagenic potential of apurinic sites in vivo has been studied by transfection of depurinated phi X174 DNA containing amber mutations into SOS-induced Escherichia coli spheroplasts. Mutagenicity is abolished by treatment of the depurinated DNA with an apurinic endonuclease from Hela cells, establishing the apurinic site as the mutagenic lesion. The frequency of copying apurinic sites in vitro was analyzed by measuring the extent of DNA synthesis using E. coli DNA polymerase I and avian myeloblastosis DNA polymerase. The inhibition of DNA synthesis by apurinic sites was less with avian myeloblastosis DNA polymerase, suggesting that this error-prone enzyme copies apurinic sites with greater frequency. Consistent with this conclusion is the observation that, upon transfection into (normal) spheroplasts, the reversion frequency of depurinated phi X174 am3 DNA copied with avian myeloblastosis virus DNA polymerase is much greater than that of the same DNA copied with E. coli DNA polymerase I. Sequence analysis of the DNA of 33 revertant phage produced by depurination indicates a preference for incorporation of deoxyadenosine opposite putative apurinic sites. The combined results indicate that mutagenesis resulting from apurinic sites is associated with bypass of these noncoding lesions during DNA synthesis.

Documentos Relacionados

• Base composition analysis of oligonucleotides containing apurinic sites.
• Importance of thiols in the repair mechanisms of DNA containing AP (apurinic or apyrimidinic) sites.
• Bypass and termination at apurinic sites during replication of single-stranded DNA in vitro: a model for apurinic site mutagenesis.
• Identification of a mammalian nuclear factor and human cDNA-encoded proteins that recognize DNA containing apurinic sites.
• Abasic site binding by the human apurinic endonuclease, Ape, and determination of the DNA contact sites.